plyr boasts several new features, most notably a new join function which should simplify what can sometimes be a difficult process in R: merging two data sets. A simplified SQL-like terminology should make it much easier to specify how the datasets should be combined. But the most significant changes to plyr may be behind the covers — this version offers a number of performance improvements that should make the process of restructuring large data frames much easier.

The ggplot2 package will also benefit from these performance improvements, and also includes a number of bug fixes to improve upon the previous version.